Heat Exchange Tube, Heat Exchange Tube Manufacturing Method, and Heat Exchanger

ABSTRACT

A heat exchange tube includes a pair of opposed facing surfaces, and an obliquely protruding part formed on at least one of the pair of facing surfaces, wherein a plurality of the obliquely protruding parts are obliquely formed to be alternately opposite in a width direction of a flow path of the heat exchange fluid, and the plurality of the obliquely protruding parts are mutually connected to form connecting parts, and when hp represents a height of the flow path of the heat exchange fluid and Wv represents a width of the obliquely protruding part in a direction orthogonal to the flow direction of the heat exchange fluid in the flow path, Wv/hp being a ratio of the width of the obliquely protruding part to the height of the flow path is equal to or greater than 1.5 and is equal to or smaller than 6.0.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of Japanese Application Patent Serial No. 2018-133728, filed Jul. 13, 2018, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a heat exchange tube, a heat exchange tube manufacturing method, and a heat exchanger.

BACKGROUND

U.S. Pat. No. 7,347,254B2 discloses a heat exchanger including flat tubes in which liquid coolant for cooling an engine flows, and a corrugate fin arranged between the flat tubes to dissipate heat of the liquid coolant to the outside air. The flat tube has vortex generators that protrude toward the inner circumference.

SUMMARY

However, according to the heat exchanger disclosed in U.S. Pat. No. 7,347,254B2, in a region where the flow velocity is relatively high, the formation of the vortex generator increases the effect of turbulence. However, at the same time, the occurrence of turbulence increases the resistance. Further, in a region where the flow velocity is relatively low, the effect of forming the vortex generator is small.

The present invention intends to improve the heat exchange efficiency while suppressing an increase in resistance.

A heat exchange tube according to an aspect of the present invention includes a pair of opposed facing surfaces on which heat exchange takes place between a first fluid flowing on an outer circumference thereof and a second fluid flowing on an inner circumference thereof, and an obliquely protruding part formed on at least one of the pair of facing surfaces in such a way as to be convex on one of the outer circumference and the inner circumference and concave on the other, the obliquely protruding part being formed obliquely along a flow direction of a heat exchange fluid, the heat exchange fluid being one of the first fluid and the second fluid flowing on the convexly formed side. A plurality of the obliquely protruding parts are obliquely formed to be alternately opposite in a width direction of a flow path of the heat exchange fluid, and the plurality of the obliquely protruding parts are mutually connected to form connecting parts. When h_(p) represents a height of the flow path of the heat exchange fluid and Wv represents a width of the obliquely protruding part in a direction orthogonal to the flow direction of the heat exchange fluid in the flow path, Wv/h_(p) being a ratio of the width of the obliquely protruding part to the height of the flow path is equal to or greater than 1.5 and is equal to or smaller than 6.0.

According to the above-mentioned aspect, forming the protrusion in such a manner that Wv/h_(p) being the ratio of the width of the obliquely protruding part to the height of the flow path is equal to or greater than 1.5 and is equal to or smaller than 6.0 can efficiently generate vertical vortices in the flow path of the heat exchange fluid. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating a heat exchanger including a heat exchange tube according to an embodiment of the present invention; and

FIG. 2A is an internal sectional diagram illustrating an upper surface of the heat exchange tube along the longer direction thereof;

FIG. 2B is an internal sectional diagram illustrating a lower surface of the heat exchange tube along the longer direction thereof;

FIG. 3A is a cross-sectional diagram taken along a line in FIG. 2A and FIG. 2B;

FIG. 3B is a graph illustrating a relationship between heat exchange performance and resistance of a fluid in relation to the relationship between the width of an obliquely protruding part and the height of a flow path;

FIG. 4A is a cross-sectional diagram illustrating a heat exchange tube according to a modified example of the embodiment illustrated in FIG. 3A;

FIG. 4B is a graph illustrating reduction rate in heat transfer coefficient in relation to the relationship of the height of the flow path and the obliquely protruding part;

FIG. 5A is an internal sectional diagram illustrating an upper surface of the heat exchange tube according to a modified example of the embodiment of the present invention along the longer direction thereof;

FIG. 5B is an internal sectional diagram illustrating a lower surface of the heat exchange tube according to the modified example of the embodiment of the present invention along the longer direction thereof;

FIG. 6 is a cross-sectional diagram taken along a line VI-VI illustrated in FIG. 5A and FIG. 5B.

FIG. 7A is a schematic configuration diagram illustrating the obliquely protruding part;

FIG. 7B is a schematic configuration diagram illustrating brazing of the obliquely protruding part and a heat conduction element;

FIG. 7C is a schematic configuration diagram illustrating a modified example of the obliquely protruding part;

FIG. 8 is a graph illustrating a relationship between resistance and heat exchange performance;

FIG. 9 is a graph derived from FIG. 8 and illustrating a relationship between the heat exchange performance and the ratio of protrusion height to the height of the flow path in the heat exchange tube;

FIG. 10 is a graph illustrating a relationship between the heat exchange performance and an inclination angle of the obliquely protruding part with respect to a flow path width direction with respect to the flow direction of the heat exchange fluid;

FIG. 11 is a graph illustrating a relationship between the heat exchange performance and the ratio of protrusion pitch to the height of the flow path;

FIG. 12 is a graph illustrating a relationship between the heat exchange performance and the ratio of obliquely protruding part pitch to the height of the flow path;

FIG. 13 is a graph illustrating a relationship between the ratio of obliquely protruding part height to the height of the flow path and the ratio of protrusion pitch to the height of the flow path;

FIG. 14 is a graph illustrating a relationship between the heat exchange performance and an inclination angle of first and second inclined parts;

FIG. 15A is a diagram illustrating the flow of a fluid passing through the obliquely protruding part;

FIG. 15B is a diagram illustrating the flow of a fluid passing through an obliquely protruding part according to a comparative example;

FIG. 16A is a diagram illustrating the flow of the fluid passing through the protruding part;

FIG. 16B is a diagram illustrating the flow of the fluid passing through the protruding part according to the comparative example;

FIG. 17 is a schematic configuration diagram illustrating a heat exchanger according to a modified example of the embodiment of the present invention;

FIG. 18 is a schematic configuration diagram illustrating a heat exchanger according to another modified example of the embodiment of the present invention; and

FIG. 19 is a schematic configuration diagram illustrating a heat exchanger according to another modified example of the embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, a heat exchange tube (hereinafter, simply referred to as “tube”) 10 according to an embodiment of the present invention and a heat exchanger 100 including the tube 10 will be described with reference to FIG. 1 to FIG. 16B.

First, the entire configuration of the heat exchanger 100 will be described with reference to FIG. 1.

The heat exchanger 100 is a radiator that is held by a radiator core support (not illustrated) and mounted on a vehicle (not illustrated). The heat exchanger 100 includes a plurality of tubes 10 stacked at intervals, a pair of tanks 20 a and 20 b arranged so as to be connected to both ends of the tubes 10 in the longer direction, and fins 30 arranged between neighboring tubes 10 and alternately stacked with the tubes 10 so as to serve as a heat conduction element.

A flow path 40 through which coolant water for exchanging heat with the outside air outside the tube 10 flows is formed on an inner circumference of the tube 10. In the present embodiment, the outside air corresponds to first fluid and the coolant water corresponds to second fluid. An example usable as the coolant water is, for example, anti-freezing fluid that is the coolant water flowing in a coolant water circuit (not illustrated) for cooling an engine (not illustrated). The coolant water can cool not only the engine but also various devices that generate heat.

The tank 20 a and the tank 20 b are each arranged in such a way as to be connected to the plurality of tubes 10 from the longer direction of the tubes 10, and temporarily stores the coolant water.

High-temperature coolant water after cooling the engine or the like flows into the tank 20 a from the coolant water circuit. The coolant water that has flowed into the tank 20 a flows through each of the plurality of tubes 10. Subsequently, when flowing through the tubes 10, the high-temperature coolant water is cooled while exchanging heat with the outside air.

The coolant water having flowed through the tubes 10 flows into the tank 20 b. The coolant water that has flowed into the tank 20 b circulates in the coolant water circuit again and cools the engine or the like.

The fins 30 are formed into a corrugated shape along the longer direction of the tube 10 and are joined to two neighboring tubes 10. The outside air introduced by vehicle traveling or an outdoor fan (not illustrated) passes around the plurality of tubes 10 and the fins 30. Therefore, the coolant water flowing inside the flow path 40 can exchange heat with the outside air via the surfaces of the tubes 10 and the fins 30. In this manner, the fins 30 promote the heat exchange between the coolant water and the outside air.

Further, the plurality of tubes 10 and fins 30 of the heat exchanger 100 function as a core part where the coolant water flowing inside the tubes 10 exchanges heat with the outside air passing therearound.

The heat exchanger 100 is suitable for an automotive heat exchanger, and is particularly suitable for use in a range where an average flow velocity Vw of the coolant water inside the tube 10 is 0.5 to 1.0 [m/s].

Next, the tube 10 will be described with reference to FIG. 2A to FIG. 6.

As illustrated in FIGS. 2A to 3A, the tube 10 includes a pair of facing surfaces 11 and 12, protrusions 15 and 16 formed on facing surfaces 11 and 12, respectively, and side surfaces 13 and 14 each connecting the pair of facing surfaces 11 and 12. The tube 10 is formed into a flat tubular shape by the facing surfaces 11 and 12 and the side surfaces 13 and 14. The flow path 40 through which the coolant water flows is formed in the space surrounded by the facing surfaces 11 and 12 and the side surfaces 13 and 14.

The tube 10 is formed of a single plate member, and as illustrated in FIG. 3A, both sides of the plate member are bent and in contact with the inner surface side of the plate member so that the cross section of the tube 10 in the width direction is substantially B-shaped, thereby forming two flow paths 40. Therefore, the pair of facing surfaces 11 and 12 facing each other are formed as a part of the single plate member. Three or more flow paths 40 may be formed in the tube 10 by changing the bending shape of the plate member.

On the facing surfaces 11 and 12, the heat exchange takes place between the outside air flowing on an outer circumference thereof and the coolant water flowing through the flow path 40 on the inner circumference.

The pair of facing surfaces 11 and 12 are arranged at intervals of a height h_(p) [mm]. This interval is the height h_(p) of the flow path 40. In the present embodiment, the height h_(p) of the flow path 40 is, for example, 1.0 mm.

As illustrated in FIG. 2A, a plurality of protrusions 15 are formed on the facing surface 11 along the flow direction of the coolant water. As illustrated in FIG. 2B, a plurality of protrusions 16 are formed on the facing surface 12 along the flow direction of the coolant water. The protrusions 15 and 16 are formed by partially deforming the facing surfaces 11 and 12. The protrusions 15 and 16 are formed by thin plate embossing. Therefore, the facing surface 11 has the same plate thickness at the positions where the protrusions 15 and 16 are formed and at the positions where the protrusions 15 and 16 are not formed. In the present embodiment, flow path width W (see FIG. 3A) of the flow path 40 is, for example, 8.0 [mm].

The protrusion 15 has a pair of ends 15 a formed on respective both sides of the tube 10 in the width direction, obliquely protruding parts 15 b inclined obliquely along the flow direction of the coolant water, and a connecting part 15 c formed in a substantially V shape with a predetermined angle in the longer direction of the tube 10. The protrusions 15 are arrayed so that the connecting parts 15 c are directed toward the flow direction of the coolant water.

Similarly, the protrusion 16 has a pair of ends 16 a formed on respective both sides of the tube 10 in the width direction, obliquely protruding parts 16 b inclined obliquely along the flow direction of the coolant water, and a connecting part 16 c formed in a substantially V shape with a predetermined angle in the longer direction of the tube 10. The protrusions 16 are arrayed so that the connecting parts 16 c are opposed to the flow direction of the coolant water.

The protrusions 15 and 16 are formed in such a way as to be concave from the outer circumference of the tube 10 and convex toward the inner circumference. The obliquely protruding parts 15 b and 16 b are formed obliquely along the flow direction of the coolant water flowing on the convexly formed side. Here, the coolant water corresponds to heat exchange fluid. The plurality of obliquely protruding parts 15 b and 16 b are formed in such a way as to be alternately opposite in the flow path width direction of the coolant water and mutually connected to form connecting parts 15 c and 16 c, respectively.

The connecting parts 15 c and 16 c are formed in curved shapes that smoothly connect the plurality of mutually adjacent obliquely protruding parts 15 b and 16 b. The connecting parts 15 c and 16 c are arcuate curved surfaces.

The protrusions 15 and 16 are each formed in such a way as to be arrayed in two rows along the flow direction of the coolant water, as illustrated in FIGS. 2A and 2B. The connecting parts 15 c and 16 c of the plurality of protrusions 15 and 16 arrayed in each row have the same orientation as the connecting parts 15 c and 16 c of the neighboring protrusions 15 and 16. That is, the orientations of the connecting parts 15 c and 16 c are the directions in which the connecting parts 15 c and 16 c are arranged in the protrusions 15 and 16. The plurality of protrusions 15 and 16 are provided side by side at intervals of pitch p [mm] in the flow direction of the coolant water.

Each of the protrusions 15 and 16 protrudes into the flow path 40 by protrusion height h [mm], as illustrated in FIG. 3A. In the present embodiment, the protrusion heights h of the protrusions 15 and 16 are, for example, 0.3 mm. When the height h_(p) of the flow path 40 is 1.0 mm as described above, the protrusion height h is 0.3 (30%) with respect to the height h_(p) of the flow path 40.

Forming the plurality of protrusions 15 on the facing surface 11 and the plurality of protrusions 16 on the facing surface 12 as described above causes the coolant water flowing in the flow path 40 to be vertically swirled in the flow path 40.

Specifically, the obliquely protruding parts 15 b and 16 b of the protrusions 15 and 16 generate small vertical vortices in the flow path 40. The small vertical vortices are formed to be arranged in the flow path 40 by the number same as the number of the obliquely protruding parts 15 b and 16 b arrayed in the flow path width direction. As a result, even in the case of using the flat tubular tube 10, a plurality of vertical vortices are evenly generated in the flow path 40 of the tube 10.

Further, the connecting parts 15 c of the protrusions 15 are arrayed in such a way as to face the opposite direction to the connecting parts 16 c of the protrusions 16, as illustrated in FIGS. 2A and 2B. Therefore, in comparison with a case where the connecting parts 15 c and 16 c of the protrusions 15 and 16 are arrayed so as to face the same direction, portions where the protrusion 15 and the protrusion 16 are overlapped with each other can be reduced to ensure a wide flow path cross section of the flow path 40, thereby allowing reduced flow path resistance.

Instead of arraying the plurality of protrusions 15 and 16 in two rows, they may be arrayed in three or more rows.

As illustrated in FIGS. 2A and 2B, Wv [mm] represents the widths of the obliquely protruding parts 15 b and 16 b in the direction orthogonal to the flow direction of the coolant water in the flow path 40, and θw [degrees] represents the inclination angles of the obliquely protruding parts 15 b and 16 b with respect to the flow path width direction with respect to the flow direction of the coolant water. In the present embodiment, the inclination angle θw is, for example, 25 [degrees].

In FIG. 3B, the horizontal axis indicates the ratio (Wv/h_(p)) of the width Wv of the obliquely protruding parts 15 b and 16 b to the height h_(p) of the flow path 40, and the vertical axis indicates the magnitude (H/ΔPw [W/deg·Pa]) of heat exchange performance H [W/deg] with respect to the magnitude of resistance ΔPw.

As illustrated in FIG. 3B, when Wv/h_(p) is in a range equal to or greater than 1.5 and equal to or smaller than 6.0, H/ΔPw is greater than that in a case where Wv/h_(p) is 0, that is, than that of a plane on which no protruding part is formed. Therefore, it is desirable to form the protrusions 15 and 16 in such a manner that Wv/h_(p), i.e., the ratio of the width Wv of the obliquely protruding parts 15 b and 16 b to the height h_(p) of the flow path 40, is equal to or greater than 1.5 and equal to or smaller than 6.0.

Further, regarding H/ΔPw, it increases sharply when Wv/h_(p) is equal to or greater than 2.0, compared to a case where Wv/h_(p) is smaller than 2.0. Further, H/ΔPw increases sharply when Wv/h_(p) is equal to or smaller than 5.0, compared to a case where Wv/h_(p) is greater than 5.0. Therefore, it is further desirable to form the protrusions 15 and 16 in such a manner that Wv/h_(p), i.e., the ratio of the width Wv of the obliquely protruding parts 15 b and 16 b to the height h_(p) of the flow path 40, is equal to or greater than 2.0 and equal to or smaller than 5.0.

Forming the protrusions 15 and 16 in which Wv/h_(p) is in the above-described range can efficiently generate vertical vortices in the flow path 40. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

According to a modified example illustrated in FIG. 4A, the side surface 14 on the outer side is formed so as to have a curved surface shape that smoothly connects the pair of facing surfaces 11 and 12. Further, the side surface 13 on the inner side is an inner wall surface that divides the flow path 40 along the flow direction of the coolant water.

Since the side surface 14 includes no straight portion and is entirely formed into the curved surface shape, the curvature radius R of the side surface 14 is R=h_(p)/2. For example, when the height h_(p) of the flow path 40 is 1.0 [mm], the curvature radius R is 0.5 [mm].

As illustrated in FIG. 4A, Wt represents the distance between the side surface 14 and the oblique protrusion 15 in the flow path width direction, and Wti represents the distance between the side surface 13 and the oblique protrusion 15 in the flow path width direction. In FIG. 4B, the horizontal axis indicates Wt/h_(p) that is the ratio of the distance Wt to the height h_(p) of the flow path 40 of the coolant water, and the vertical axis indicates the reduction rate in heat transfer coefficient.

As illustrated in FIG. 4B, regarding the reduction rate in heat transfer coefficient, the gradient of the curve changes at a border where Wt/h_(p) is 3.0. That is, Wt/h_(p)=3.0 is a point of inflection of the reduction rate in heat transfer coefficient. When Wt/h_(p) becomes greater than 3.0, the deterioration allowance of heat transfer coefficient increases. Further, when Wt/h_(p) becomes smaller than R, working and processing becomes difficult although the heat transfer coefficient becomes higher. Therefore, it is desirable that Wt/h_(p), i.e., the ratio of the distance Wt to the height h_(p) of the flow path 40 of the coolant water, is equal to or greater than R and equal to or smaller than 3.0 (R≤Wt/h_(p)≤3.0).

As a result, since the side surface 14 is formed into the arcuate curved surface, the resistance of the vertical vortex generated inside the flow path 40 is small and the performance can be prevented from deteriorating.

Further, the distance Wti between the side surface 13 and the oblique protrusion 15 in the flow path width direction is shorter than the distance Wt between the side surface 14 and the oblique protrusion 15 in the flow path width direction.

It is difficult to form the inner side surface 13 into a curved surface shape like the side surface 14. However, setting the distance Wti to be shorter than the distance Wt can prevent the performance from deteriorating.

Next, the tube 10 according to a modified example of the embodiment of the present invention will be described with reference to FIG. 5A to FIG. 6. In the following modified example of the embodiment, configurations similar to those in the embodiment of the present invention are denoted by the same symbols, and duplicated descriptions will not be repeated, appropriately.

The protrusion 15 is formed in such a manner so as to have three connecting parts 15 c in the width direction of the tube 10, as illustrated in FIGS. 5A and 5B. That is, the protrusion 15 is formed in a substantially W shape. In this case, when forming the tube 10 by thin plate embossing, the number of ends 15 a is small and therefore the protrusion 15 can be easily formed.

Further, in this modified example, the protrusions 15 are formed on one facing surface 11 and no protruding part is formed on the other facing surface 12.

In this manner, the protrusion 15 may be formed in such a manner that the number of the connecting parts 15 c is greater than the number of the ends 15 a that are not connected to other neighboring obliquely protruding part 15 b.

As illustrated in FIG. 5A, the obliquely protruding part 15 b is linearly formed. The obliquely protruding part 15 b between neighboring connecting parts 15 c is shorter in length than the connecting part 15 c. This improves formability of the protrusion 15.

In a case where a plurality of protrusions 15 and 16 are provided on both of the facing surfaces 11 and 12, respectively, not only the protrusion 15 but also the protrusion 16 may be formed so as to have four or more connecting parts 16 c in the width direction of the tube 10. Similar effects can be exerted.

In this manner, the width Wv of the obliquely protruding parts 15 b and 16 b is determined according to the height h_(p) and the width W of the flow path 40, and the number of the connecting parts 15 c and 16 c can be increased as necessary. It is desirable that the gap between the side surfaces 13 and 14 and the protrusions 15 and 16 of the tube 10 be smaller, and it is further desirable that no gap is provided between the obliquely protruding parts 15 b and 16 b neighboring in the width direction of the flow path 40.

Next, the shape of the obliquely protruding part 15 b will be described with reference to FIG. 7A to FIG. 16B. Since the obliquely protruding part 16 b is configured in the same manner as the obliquely protruding part 15 b, only the obliquely protruding part 15 b will be described below and the obliquely protruding part 16 b will not be described. Since the ends 15 a and 16 a and the connecting parts 15 c and 16 c are also formed in the same shape as the obliquely protruding parts 15 b and 16 b along the flow direction of the coolant water, detailed description thereof will be omitted here.

FIG. 7A and FIG. 7B are cross-sectional diagrams (cross-sectional diagrams taken along a line VIIA-VIIA in FIG. 2A) illustrating the obliquely protruding part 15 b along the flow direction of the coolant water flowing in the flow path 40. FIG. 7C is a cross-sectional diagram (a cross-sectional diagram taken along a line VIIC-VIIC in FIG. 2A) illustrating the obliquely protruding part 15 b in a cross section orthogonal to the obliquely protruding parts 15 b and 16 b. As illustrated in FIG. 7A, the obliquely protruding part 15 b includes a first inclined part 51 in which the amount of protrusion increases along the flow direction of the coolant water and a second inclined part 52 that is formed continuously with the first inclined part 51 and in which the amount of protrusion decreases along the flow direction of the coolant water.

The first inclined part 51 and the second inclined part 52 are provided so as to be inclined at an inclination angle θ [degrees] in the plate thickness direction with respect to the facing surface 11. In the present embodiment, the inclination angle θ in the plate thickness direction is, for example, 10 [degrees]. Since the protrusion 15 is formed to have the protrusion height h [mm], the shape is defined by the protrusion height h and the inclination angle θ. The protrusion height h will be described in detail below with reference to FIG. 8 to FIG. 13. The inclination angle θ will be described in detail below with reference to FIG. 14 to FIG. 16B.

The first inclined part 51 and the second inclined part 52 are inclined in such a way to prevent the coolant water from separating and generate a vertical vortex in the coolant water. Therefore, the occurrence of turbulence due to the separation is suppressed, and the coolant water flows in such a way as to be vertically swirled along the obliquely protruding parts 15 b and 16 b. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

The first inclined part 51 is connected to the facing surface 11 via an arcuate curved surface having a radius r1 being a first radius. The first inclined part 51 and the second inclined part 52 are connected via an arcuate curved surface having a radius r2 being a second radius. As described above, a protrusion end 15 d of the obliquely protruding part 15 b connecting the first inclined part 51 and the second inclined part 52 is an arcuate curved surface. As a result, the cross-sectional change is smooth and accordingly the resistance can be reduced. The second inclined part 52 is connected to the facing surface 11 via an arcuate curved surface having a radius r3 being a third radius. These radii r1, r2, and r3 are set to be greater than the protrusion height h of the obliquely protruding part 15 b. As a result, since the facing surface 11, the first inclined part 51, and the second inclined part 52 are smoothly connected, it is possible to further suppress the separation of the coolant water.

As illustrated in FIG. 7A, since the protrusion height h is small, when the tube 10 and the fin 30 are brazed, the protrusion 15 is brazed to the fin 30 by a brazing part 53 serving as a joint portion. As a result, since the brazing part 53 fills between the tube 10 and the fin 30 and no gap is formed, the amount of heat transfer between the tube 10 and the fin 30 can be increased.

As illustrated in FIG. 7B, when the protrusion 15 is divided into a region A on the base end side and a region B on the distal end side, the brazing part 53 may be formed in such a way as to include the region A on the base end side and at least a part of the region B on the distal end side. In this case, the brazing part 53 brazes a region of more than half of the protrusion 15 to the fin 30. Also in this case, since the gap between the tube 10 and the fin 30 is filled by the brazing part 53 and reduced, the amount of heat transfer between the tube 10 and the fin 30 can be increased.

Further, as illustrated in FIG. 7C, the first inclined part 51 and the second inclined part 52 may be formed only by curved surface portions without including straight portions. In this case, the inclination angle θ in the plate thickness direction is an angle of a tangential line relative to the facing surface 11 at a point of inflection (a point having the largest gradient) between a curved surface continuous from a base end 11 a connected to the facing surface 11 and a curved surface continuous from the protrusion end 15 d.

When ra represents a curvature radius of a concavely formed side at the protrusion end 15 d of the obliquely protruding part 15 b, the curvature radius ra is smaller than the protrusion height h of the obliquely protruding part 15 b. As a result, even if the protrusion height h is the same, a width W_(L) of the obliquely protruding part 15 b in the length direction of the coolant water can be reduced by an amount corresponding to the reduction of the curvature radius ra at the protrusion end 15 d. Therefore, the contact area between the fin 30 and the tube 10 can be increased.

Further, when rb and rc represent curvature radii of convexly formed sides at the base ends 11 a, which are formed on both sides of the protrusion end 15 d of the obliquely protruding part 15 b, the curvature radius ra is smaller than the curvature radius rb and the curvature radius rc. As a result, since the curvature radii rb and rc are greater than the curvature radius ra, the brazing material smoothly enters at the time of brazing. Therefore, the contact area between the fin 30 and the tube 10 can be increased.

Next, the ratio of the protrusion height h to the height h_(p) of the flow path 40 will be described with reference to FIG. 8 and FIG. 9.

In FIG. 8, black circular plots (●) indicate a case of a plane on which no protruding part is formed. Black rhomboidal plots (♦) indicate a case where V-shaped protrusions 15 and 16 of protrusion height h=0.1 [mm] are formed. Black square plots (▪) indicate a case where W-shaped protrusions 15 of protrusion height h=0.2 [mm] are formed. White triangular plots (Δ) indicate a case where V-shaped protrusions 15 and 16 of protrusion height h=0.2 [mm] are formed. White rhomboidal plots (⋄) indicate a case where V-shaped protrusions 15 and 16 of protrusion height h=0.3 [mm] are formed. The height h_(p) of the flow path 40 in the tube 10 is 0.9 [mm].

Further, as illustrated in FIG. 8, in the case where the V-shaped protrusions 15 of protrusion height h=0.3 [mm] are formed, in the case where the V-shaped protrusions 15 and 16 of protrusion height h=0.2 [mm] are formed, and in the case where the W-shaped protrusions 15 of protrusion height h=0.2 [mm] are formed, the heat exchange performance H [W/deg] of the heat exchanger 100 is higher in comparison with the case of the plane on which no protruding part is formed. That is, in these cases, the heat exchange performance H can be enhanced by the formation of the protrusion 15 or the protrusions 15 and 16, as compared with the case where no protruding part is formed.

FIG. 9 illustrates a graph derived from FIG. 8. In FIG. 9, the horizontal axis indicates the ratio (h/h_(p) [%]) of the protrusion height h of the protrusions 15 and 16 to the height h_(p) of the flow path 40 in the tube 10, and the vertical axis indicates the magnitude (H/ΔPw [W/deg·kPa]) of the heat exchange performance H [W/deg] with respect to the magnitude of the resistance ΔPw. The graph illustrated in FIG. 9 plots data obtained when the inclination angle θ of the first inclined part 51 and the second inclined part 52 is 10 [degrees] and the flow velocity Vw of the coolant water is 0.7 [m/s].

As illustrated in FIG. 9, in a range where the protrusion height h of the protrusions 15 and 16 is equal to or greater than 0.1 (10%) and equal to or smaller than 0.5 (50%) of the height h_(p) of the flow path 40, H/ΔPw takes values greater than those when the protrusion height h is 0, that is, those in the case of the plane on which no protruding part is formed. Therefore, it is desirable to set the protrusion height h of the protrusions 15 and 16 to be equal to or greater than 0.1 and equal to or smaller than 0.5 of the height h_(p) of the flow path 40.

Next, the shapes of the protrusions 15 and 16, and the arrangement of the protrusions 15 and 16 in the flow path 40, will be described with reference to FIG. 10 to FIG. 13.

In FIG. 10, the horizontal axis indicates the inclination angle θw [degrees] of the obliquely protruding parts 15 b and 16 b with respect to the flow path width direction with respect to the flow direction of the coolant water, and the vertical axis indicates the magnitude (H/ΔPw [W/deg·kPa]) of the heat exchange performance H [W/deg] with respect to the magnitude of the resistance ΔPw. In FIG. 11 and FIG. 12, the horizontal axis indicates the ratio (p/h_(p)) of the pitch p of the protrusions 15 and 16 to the height h_(p) of the flow path 40, and the vertical axis indicates the magnitude (H/ΔPw [W/deg·kPa]) of the heat exchange performance H [W/deg] with respect to the magnitude of the resistance ΔPw. In FIG. 13, the horizontal axis indicates the ratio (h/h_(p)) of the protrusion height h of the protrusions 15 and 16 to the height h_(p) of the flow path 40, and the vertical axis indicates the ratio (p/h_(p)) of the pitch p of the protrusions 15 and 16 to the height h_(p) of the flow path 40.

FIG. 10 illustrates optimum inclination angle θw [degrees] of the obliquely protruding part 15 b with respect to the flow direction of the coolant water. In FIG. 10, a straight line indicated by a two-dot chain line indicates H/ΔPw when a square protruding part having a straight line perpendicular to the flow direction of the coolant water is provided, instead of V shape. As illustrated in FIG. 10, when the inclination angle θw of the obliquely protruding parts 15 b and 16 b in the flow path width direction is equal to or greater than 15 degrees and equal to or smaller than 38 degrees, H/ΔPw is larger than that in the case of providing the square protruding part. Therefore, it is desirable to form the obliquely protruding parts 15 b and 16 b in such a manner that the inclination angle θw in the flow path width direction is equal to or greater than 15 degrees and equal to or smaller than 38 degrees.

It is further desirable to form the obliquely protruding parts 15 b and 16 b in such a manner that the inclination angle θw in the flow path width direction is equal to or greater than 18 degrees and equal to or smaller than 30 degrees.

In FIG. 11, black circular plots (●) indicate the case of protrusion height h=0.1 [mm] (h/h_(p)=0.1). Black rhomboidal plots (♦) indicate the case of protrusion height h=0.2 [mm] (h/h_(p)=0.2). Black square plots (▪) indicate the case of protrusion height h=0.3 [mm] (h/h_(p)=0.3). Black triangular plots (▴) indicate the case of protrusion height h=0.4 [mm] (h/h_(p)=0.4). White circular plots (∘) indicate the case of protrusion height h=0.5 [mm] (h/h_(p)=0.5).

FIG. 11 illustrates H/ΔPw in each of optimum values 0.1 to 0.5 (see FIG. 9) of the protrusion height h, in the case of the optimum inclination angle θw [degrees] illustrated in FIG. 10 (when θw is about 23 [degrees]). As illustrated in FIG. 11, when the protrusion height h is 0.1 to 0.5, H/ΔPw changes with the same tendency.

In FIG. 12, black triangular plots (▴) are values in the case of protrusion height h=0.4 [mm] (h/h_(p)=0.4) in FIG. 11. In FIG. 10, white triangular plots (Δ) are values in the case of inclination angle θw (in the case of 15 degrees or 38 degrees) corresponding to the lower limit value of H/ΔPw illustrated in FIG. 10. In FIG. 12, since the protrusion height h changes with the same tendency in each case of 0.1 to 0.5, the case of h=0.4 [mm] is illustrated as an example.

As illustrated in FIG. 12, in the case of the optimum inclination angle θw [degrees] indicated by a solid line, H/ΔPw increases sharply when p/h_(p) becomes equal to or greater than 12.5, compared to the case of smaller than 12.5, and also H/ΔPw increases sharply when p/h_(p) becomes equal to or smaller than 25.0, compared to the case of greater than 25.0. Similarly, in the case of the inclination angle θw [degrees] in the lower limit value indicated by a dotted line, H/ΔPw increases sharply when p/h_(p) becomes equal to or greater than 12.5, compared to the case of smaller than 12.5, and also H/ΔPw increases sharply when p/h_(p) becomes equal to or smaller than 25.0, compared to the case of greater than 25.0. The values of p/h_(p) corresponding to h/h_(p) at this time are plotted in FIG. 13, as the upper limit value (25.0) and the lower limit value (12.5) in the case of h=0.4 [mm].

In this manner, approximate curves drawn by plotting the upper limit values and the lower limit values of p/h_(p) in respective cases where the protrusion height h is 0.1 to 0.5 are illustrated in FIG. 13. When x represents h/h_(p) and y represents p/h_(p), the approximate curve indicating the upper limit values can be defined by y=107.14x²+4.7143x+5.9, and the approximate curve indicating the lower limit values can be defined by y=139.29x²+32.071x+3.

Accordingly, it is desirable that the inclination angle θw of the obliquely protruding parts 15 b and 16 b with respect to the flow path width direction with respect to the flow direction of the coolant water is equal to or greater than 15 degrees and equal to or smaller than 38 degrees. When h represents the protrusion height of the obliquely protruding parts 15 b and 16 b formed convexly, it is desirable that h/h_(p) being the ratio of the protrusion height h to the flow path height h_(p) is equal to or greater than 0.1 and equal to or smaller than 0.5, and the plurality of obliquely protruding parts 15 b and 16 b are formed in the flow direction of the coolant water. When p represents the interval (pitch) between neighboring obliquely protruding parts 15 b and 16 b, x represents h/h_(p) being the ratio of the protrusion height h to the flow path height h_(p), and y represents p/h_(p) being the ratio of the pitch p to the flow path height h_(p), it is desirable that the pitch p, the flow path height h_(p), and the protrusion height h have values between y=107.14x²+4.7143x+5.9 and y=139.29x²+32.071x+3.

When vertical vortices occur in the entire flow path 40, the heat exchange performance H improves. The size of the vertical vortex is determined by the height h_(p) of the flow path 40 and the protrusion height h of the protrusions 15 and 16. Therefore, there is an optimum value for the ratio of the protrusion height h of the protrusions 15 and 16 to the height h_(p) of the flow path 40. On the other hand, finely setting the pitch p of the protrusions 15 and 16 can enhance the vertical vortex and can improve the heat exchange performance H with the coolant water. However, since the number of recesses on the surface where the protrusions 15 and 16 are concavely formed increases, heat conduction from the tube 10 to the fin 30 is hindered. Therefore, there is an optimum value for the ratio of the pitch p of the protrusions 15 and 16 to the height h_(p) of the flow path 40.

In view of the above, in the present embodiment, adopting the above-described arrangement of the protrusions 15 and 16 can efficiently generate vertical vortices in the flow path 40. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Next, the magnitude of the inclination angle θ of the first inclined part 51 and the second inclined part 52 will be described with reference to FIG. 14 to FIG. 16B.

In FIG. 14, the horizontal axis indicates the inclination angle θ [degrees] of the first inclined part 51 and the second inclined part 52 in the plate thickness direction, and the vertical axis indicates the magnitude of the heat exchange performance H [W/deg] with respect to the magnitude of the resistance ΔPw (H/ΔPw [W/deg·kPa]). In FIG. 14, black rhomboidal plots (♦) indicate a case where the inclination angle θw of the obliquely protruding part 15 b in the flow path width direction is 15 [degrees]. White square plots (□) indicate a case where the inclination angle θw of the obliquely protruding part 15 b in the flow path width direction is 30 [degrees]. Black square plots (▪) indicate a case where the inclination angle θw of the obliquely protruding part 15 b in the flow path width direction is 45 [degrees].

As illustrated in FIG. 14, at any inclination angle θw, H/ΔPw increases sharply when the inclination angle θ in the plate thickness direction becomes equal to or greater than 5 [degrees], compared to the case of smaller than 5 [degrees], and also H/ΔPw increases sharply when the inclination angle θ becomes equal to or smaller than 20 [degrees], compared to the case of greater than 20 [degrees]. Therefore, it is desirable to form the first inclined part 51 and the second inclined part 52 so as to have the inclination angle θ in the plate thickness direction that is equal to or greater than 5 [degrees] and equal to or smaller than 20 [degrees].

In examples illustrated in FIG. 15A and FIG. 16A, an inclination angle θ1 [degrees] is in the range equal to or greater than 5 [degrees] and equal to or smaller than 20 [degrees] (e.g., 01=5 [degrees]). In this case, the coolant water flows in such a way as to be vertically swirled on the downstream side of the protrusions 15 and 16 without separating from the first inclined part 51 and the second inclined part 52.

On the other hand, in examples illustrated in FIG. 15B and FIG. 16B, an inclination angle θ₂ [degrees] is set to be greater than 20 [degrees] (e.g., 02=35 [degrees]). Also in this case, the coolant water flows in such a way as to be vertically swirled on the downstream side of the protrusions 15 and 16. However, the coolant water flows along the first inclined part 51 and then separates from the second inclined part 52 to form turbulence.

In this manner, the obliquely protruding parts 15 b and 16 b are inclined at the inclination angle θ so as to generate vertical vortices in the coolant water without the separation of the coolant water. Therefore, the occurrence of turbulence due to the separation is suppressed, and the coolant water flows along the obliquely protruding part 15 b so as to be vertically swirled. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Next, heat exchangers 200, 300, and 400 according to various modified examples of the present invention will be described with reference to FIG. 17 to FIG. 19, respectively.

The heat exchanger 200 illustrated in FIG. 17 includes a casing 201 that forms the flow path 40 of the coolant water being the first fluid, the tubes 10 housed in the casing 201, and the fins 30 provided in the tubes 10.

The heat exchanger 200 is an EGR cooler that cools high-temperature EGR (Exhaust Gas Recirculation) gas recirculated to an engine (not illustrated) with the coolant water of the engine. The heat exchanger 200 is different from the heat exchanger 100 in that the protrusions 15 and 16 are provided on the outer circumference of the tube 10.

In the heat exchanger 200, the coolant water circulating in the casing 201 flows in the flow path 40 on the outer circumference of the tube 10. In FIG. 17, the coolant water flows in the direction perpendicular to the paper surface. The EGR gas flows through the inner circumference of the tube 10.

The obliquely protruding parts 15 b and 16 b are formed on the facing surfaces 11 and 12 so as to be convex on the outer circumference and concave from the inner circumference. Also in this example, the coolant water corresponds to the heat exchange fluid.

In this manner, the obliquely protruding parts 15 b and 16 b are formed, on at least one of the pair of facing surfaces 11 and 12, so as to be convex on one of the outer circumference and the inner circumference and concave on the other, and are formed obliquely along the flow direction of the heat exchange fluid that is one of the first fluid and the second fluid flowing on the convexly formed side.

The heat exchanger 300 illustrated in FIG. 18 is different from the heat exchanger 200 in that linearly protruding parts 17 are further provided.

The linearly protruding part 17 is linearly formed so as to guide the coolant water along the protrusions 15 and 16. In FIG. 18, the coolant water flows in the direction perpendicular to the paper surface. As a result, the coolant water flows in such a way as to be vertically swirled between the pair of linearly protruding parts 17.

In these cases, the obliquely protruding parts 15 b and 16 b formed obliquely along the flow direction of the coolant water include the first inclined part 51 and the second inclined part 52 that are inclined so as to generate vertical vortices in the coolant water without the separation of the coolant water. The occurrence of turbulence due to the separation is suppressed, and the coolant water flows along the obliquely protruding parts 15 b and 16 b so as to be vertically swirled. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

The heat exchanger 400 illustrated in FIG. 19 includes the tube 10 so as to cause a heat-generation element 60, which abuts on the outer circumference of one facing surface 11, to dissipate heat. The obliquely protruding parts 16 b are not formed on one facing surface 11 that abuts on the heat-generation element 60 and are formed in such a way as to protrude on the inner circumference of the other facing surface 12. In FIG. 19, the coolant water flows in the direction perpendicular to the paper surface.

The heat-generation element 60 is, for example, an electronic component or the like, such as a storage battery mounted on a vehicle, an inverter that drives an electric motor for causing the vehicle to travel, or an Insulated Gate Bipolar Transistor (IGBT) used for the inverter.

The obliquely protruding parts 16 b are formed on the facing surface 12 so as to be convex on the inner circumference and concave from the outer circumference. Also in this example, the coolant water corresponds to the heat exchange fluid.

Also in this case, forming the obliquely protruding parts 16 b can generate vertical vortices in the coolant water flowing through the flow path 40 in the tube 10, while ensuring a sufficient contact area between the heat-generation element 60 and the tube 10. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

According to the above-described embodiments, the following effects can be exerted.

The tube 10 includes the pair of opposed facing surfaces 11 and 12 on which heat exchange takes place between the outside air flowing on the outer circumference thereof and the coolant water flowing on the inner circumference thereof, and the obliquely protruding parts 15 b and 16 b formed on at least one of the pair of facing surfaces 11 and 12 in such a way as to be convex on one of the outer circumference and the inner circumference and concave on the other, the obliquely protruding part is formed obliquely along the flow direction of the coolant water of the outside air and the coolant water, and the coolant water flows on the convexly formed side. The plurality of obliquely protruding parts 15 b and 16 b are obliquely formed to be alternately opposite in the width direction of the flow path 40 of the coolant water and the plurality of the obliquely protruding parts are mutually connected to form the connecting parts 15 c and 16 c. When h_(p) represents the height of the flow path 40 of the coolant water and Wv represents the width of the obliquely protruding parts 15 b and 16 b in the direction orthogonal to the flow direction of the coolant water in the flow path 40, Wv/h_(p) being the ratio of the width of the obliquely protruding parts 15 b and 16 b to the height of the flow path 40 is equal to or greater than 1.5 and equal to or smaller than 6.0.

Further, Wv/h_(p) being the ratio of the width of the obliquely protruding parts 15 b and 16 b to the height of the flow path 40 is equal to or greater than 2.0 and equal to or smaller than 5.0.

According to these configurations, forming the protrusions 15 and 16 so that Wv/h_(p) is in the above-described range can efficiently generate vertical vortices in the flow path 40. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Further, the obliquely protruding parts 15 b and 16 b include the first inclined part 51 that is inclined in such a manner that the amount of protrusion increases along the flow direction of the coolant water and generates a vertical vortex in the coolant water, and the second inclined part 52 that is inclined in such a manner that the amount of protrusion decreases along the flow direction of the coolant water and generates a vertical vortex in the coolant water. The protrusion end 15 d connecting the first inclined part 51 and the second inclined part 52 is an arcuate curved surface.

According to this configuration, the occurrence of turbulence due to the separation is suppressed, and the coolant water flows in such a way as to be vertically swirled along the obliquely protruding parts 15 b and 16 b. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence. Further, the protrusion end 15 d is the arcuate curved surface, and therefore the cross-sectional change is smooth and the resistance can be reduced.

Further, the inclination angle θw of the obliquely protruding parts 15 b and 16 b with respect to the flow path width direction with respect to the flow direction of the coolant water is equal to or greater than 15 degrees and equal to or smaller than 38 degrees. When h represents the height of the convexly formed protrusion of the obliquely protruding parts 15 b and 16 b, h/h_(p) being the ratio of the protrusion height h to the flow path height h_(p) is equal to or greater than 0.1 and equal to or smaller than 0.5. The plurality of obliquely protruding parts 15 b and 16 b are formed in the flow direction of the coolant water. When p represents the interval (pitch) between neighboring obliquely protruding parts 15 b and 16 b, x represents h/h_(p) being the ratio of the protrusion height h to the flow path height h_(p), and y represents p/h_(p) being the ratio of the pitch p to the flow path height h_(p), the pitch p, the flow path height h_(p), and the protrusion height h have values between y=107.14x²+4.7143x+5.9 and y=139.29x²+32.071x+3.

According to this configuration, adopting the above-described arrangement of the protrusions 15 and 16 can efficiently generate vertical vortices in the flow path 40. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Further, the facing surface 11 has the plate thickness same between a position where the obliquely protruding part 15 b is formed and a position where the obliquely protruding part 15 b is not formed. The fin 30 contacts one of the outer circumference and the inner circumference where the obliquely protruding part 15 b is concavely formed. When ra represents the curvature radius of the protrusion end 15 d of the obliquely protruding part 15 b on the concavely formed side in a cross section orthogonal to the obliquely protruding part 15 b, and h represents the height of the convexly formed protrusion of the obliquely protruding part 15 b, the curvature radius ra is smaller than the protrusion height h.

According to this configuration, even if the protrusion height h is the same, the width W_(L) of the obliquely protruding part 15 b in the length direction of the coolant water can be reduced by an amount corresponding to the reduction of the curvature radius ra at the protrusion end 15 d. Therefore, the contact area between the fin 30 and the tube 10 can be increased.

Further, when rb and rc represent curvature radii of convexly formed sides at the base ends 11 a, and the base ends 11 a are formed on both sides of the protrusion end 15 d of the obliquely protruding part 15 b, the curvature radius ra is smaller than the curvature radius rb and the curvature radius rc.

According to this configuration, since the curvature radii rb and rc are greater than the curvature radius ra, the brazing material smoothly enters at the time of brazing. Therefore, the contact area between the fin 30 and the tube 10 can be increased.

Further, the tube 10 includes the pair of side surfaces 14 each connecting the pair of facing surfaces 11 and 12 to form the flow path 40 of the coolant water. The side surface 14 is formed so as to have a curved surface shape that smoothly connects the pair of facing surfaces 11 and 12. When R represents the curvature radius of the side surface 14, and Wt represents the distance between the side surface 14 and the oblique protrusion 15 in the flow path width direction, Wt/h_(p) being the ratio of the distance Wt to the height h_(p) of the flow path 40 of the coolant water is equal to or greater than R and equal to or smaller than 3.0.

According to this configuration, since the side surface 14 is formed into the arcuate curved surface, the resistance of vertical vortex generated inside the flow path 40 is small and the performance can be prevented from deteriorating.

Further, the tube 10 includes the side surface 13 that divides the flow path 40 along the flow direction of the coolant water, and the distance Wti between the side surface 13 and the oblique protrusion 15 in the flow path width direction is shorter than the distance Wt between the side surface 14 and the oblique protrusion 15 in the flow path width direction.

According to this configuration, it is difficult to form the inner side surface 13 into a curved surface shape like the side surface 14. However, setting the distance Wti to be shorter than the distance Wt can prevent the performance from deteriorating.

Further, the tube 10 includes the pair of opposed facing surfaces 11 and 12 on which heat exchange takes place between the outside air flowing on the outer circumference thereof and the coolant water flowing on the inner circumference thereof, and the obliquely protruding parts 15 b and 16 b formed on at least one of the pair of facing surfaces 11 and 12 in such a way as to be convex on one of the outer circumference and the inner circumference and concave on the other, and formed obliquely along the flow direction of the coolant water flowing on the convexly formed side, of the outside air and the coolant water. The obliquely protruding parts 15 b and 16 b include the first inclined part 51 that is inclined in such a manner that the amount of protrusion increases along the flow direction of the coolant water and generates a vertical vortex without separation of the coolant water, and the second inclined part 52 that is formed continuously with the first inclined part 51 and is inclined in such a manner that the amount of protrusion decreases along the flow direction of the coolant water, and generates a vertical vortex without separation of the coolant water.

According to this configuration, the obliquely protruding parts 15 b and 16 b formed obliquely along the flow direction of the coolant water includes the first inclined part 51 and the second inclined part 52 inclined so as to generate vertical vortices in the coolant water without the separation of the coolant water. The occurrence of turbulence due to the separation is suppressed, and the coolant water flows in such a way as to be vertically swirled along the obliquely protruding parts 15 b and 16 b. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Further, the inclination angles θ of the first inclined part 51 and the second inclined part 52 in the plate thickness direction are equal to or greater than 5 [degrees] and equal to or smaller than 20 [degrees].

According to this configuration, the obliquely protruding parts 15 b and 16 b are inclined in the plate thickness direction at the inclination angle θ at which the coolant water is not separated to be vertically swirled. Therefore, the occurrence of turbulence due to the separation is suppressed, and the coolant water flows along the obliquely protruding part 15 b in such a way as to be vertically swirled. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Further, the first inclined part 51 is connected to the facing surface 11 via the arcuate curved surface having the radius r1. The second inclined part 52 is connected to the first inclined part 51 via the arcuate curved surface having the radius r2, and is connected to the facing surface 11 via the arcuate curved surface having the radius r3. The radius r1, the radius r2, and the radius r3 are greater than the protrusion height h of the obliquely protruding parts 15 b and 16 b.

According to this configuration, since the facing surface 11, the first inclined part 51, and the second inclined part 52 are smoothly connected, it is possible to further suppress the separation of the coolant water.

Further, the plurality of obliquely protruding parts 15 b and 16 b are connected in the flow path width direction of the coolant water and formed as a single portion.

According to this configuration, when forming the tube 10 by thin plate embossing, the number of ends 15 a is small and therefore the protrusion 15 can be easily formed.

Further, the connecting part 15 c is formed in a curved shape that smoothly connects the plurality of neighboring obliquely protruding parts 15 b. The obliquely protruding part 15 b between the neighboring connecting parts 15 c is linearly formed and is shorter in length than the connecting part 15 c.

According to this configuration, the formability of the protrusion 15 can be improved.

Further, the heat exchangers 100, 200, and 300, which include the tube 10 and the fin 30 provided so as to abut on the concavely formed sides of the obliquely protruding parts 15 b and 16 b of the facing surfaces 11 and 12, further include the brazing part 53 for brazing the fin 30 to the tube 10 so as to include at least a part of the region B on the protrusion end side of the first inclined part 51 and the second inclined part 52 of the obliquely protruding parts 15 b and 16 b.

According to this configuration, since the brazing part 53 fills between the tube 10 and the fin 30 so as to reduce the size or form no gap, the amount of heat transfer between the tube 10 and the fin 30 can be increased.

Further, in the heat exchanger 400 that includes the tube 10 and causes the heat-generation element 60, which abuts on the outer circumference of one of the facing surfaces 11 and 12, to dissipate heat, the obliquely protruding parts 15 b and 16 b are not formed on one facing surface 11 that abuts on the heat-generation element 60 and are formed in such a way as to protrude on the inner circumference of the other facing surface 12.

According to this configuration, when the tube 10 is applied to the heat exchanger 400 that cools the heat-generation element 60, no protruding part is formed on the facing surface 11 that abuts on the heat-generation element 60 and the obliquely protruding parts 16 b are formed on the facing surface 12 that is not brought into contact with the heat-generation element 60. As a result, while ensuring a sufficient contact area between the heat-generation element 60 and the tube 10, vertical vortices can be generated in the coolant water flowing through the flow path 40 in the tube 10. Accordingly, it is possible to improve the heat exchange efficiency while suppressing an increase in resistance due to the occurrence of turbulence.

Although the embodiments of the present invention have been described in the above, the above-mentioned embodiments merely illustrate a part of application examples of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configurations in the above-mentioned embodiments.

For example, the heat exchanger 100 may include a plurality of paths formed in such a manner that the coolant water having passed through one tube 10 can be recirculated into another tube 10. For example, to form the plurality of paths, partitions for partitioning the coolant water may be provided in tanks 20 a and 20 b. As a result, since the longer flow path 40 can be ensured compared to the case where the plurality of paths are not formed, it is possible to improve the heat exchange efficiency between the outside air and the coolant water.

Further, the above-described embodiments can be applied not only to the heat exchanger 100 but also to an outdoor heat exchanger of a refrigeration cycle, for example. In this case, a refrigerant such as HFC-134a may be used, instead of the coolant water, as the fluid flowing inside the tube 10.

Further, the above embodiments can be applied to, for example, an intercooler of a supercharger or the like. In this case, compressed intake air is used, instead of the outside air, as the fluid flowing outside the tube 10.

Further, the fluid flowing outside the tube 10 is not limited to the gas. For example, a liquid such as an Automatic Transmission Fluid (ATF) oil circulating in an automatic transmission may be used. 

1.-16. (canceled)
 17. A heat exchange tube comprising: a pair of opposed facing surfaces on which heat exchange takes place between a first fluid flowing on an outer circumference thereof and a second fluid flowing on an inner circumference thereof; an obliquely protruding part formed on at least one of the pair of facing surfaces in such a way as to be convex on one of the outer circumference and the inner circumference and concave on the other, the obliquely protruding part being formed obliquely along a flow direction of a heat exchange fluid, the heat exchange fluid being one of the first fluid and the second fluid flowing on the convexly formed side; and a pair of side surfaces each connecting the pair of facing surfaces to form a flow path of the heat exchange fluid, wherein a plurality of the obliquely protruding parts are obliquely formed to be alternately opposite in a width direction of a flow path of the heat exchange fluid, and the plurality of the obliquely protruding parts are mutually connected to form connecting parts, the side surface is formed so as to have a curved surface shape smoothly connecting the pair of facing surfaces, and when hp represents the height of the flow path of the heat exchange fluid, R represents a curvature radius of the side surface, and Wt represents a distance between the side surface and the obliquely protruding part in a flow path width direction, Wt/hp being a ratio of the distance to a height of the flow path of the heat exchange fluid is equal to or greater than R and is equal to or smaller than 3.0.
 18. The heat exchange tube according to claim 17, further comprising: an inner wall surface dividing the flow path along the flow direction of the heat exchange fluid, wherein a distance Wti between the inner wall surface and the obliquely protruding part in the flow path width direction is shorter than the distance Wt between the side surface and the obliquely protruding part in the flow path width direction.
 19. The heat exchange tube according to claim 17, wherein the connecting part is formed in a curved shape smoothly connecting neighboring plurality of obliquely protruding parts, and the obliquely protruding part between neighboring connecting parts is linearly formed and is shorter in length than the connecting part.
 20. The heat exchange tube according to claim 17, wherein when Wv represents a width of the obliquely protruding part in a direction orthogonal to the flow direction of the heat exchange fluid in the flow path, Wv/hp being a ratio of the width of the obliquely protruding part to the height of the flow path is equal to or greater than 1.5 and is equal to or smaller than 6.0. 